1. Field of the Invention
The present invention relates to a portable collimator for adjusting video cameras, and more particularly to an improved compact and light weight collimator adapted to use with video cameras for adjusting an optical system of the video cameras.
2. Description of the Prior Art
Upon servicing a video camera involving such as an imaging device, an optical system of the video camera often requires adjustments, this is for verifying that a light of the taking object is properly focused on an imaging plane of the imaging device in the video camera. In order to adjust the optical system to a distance of "infinity", a parallel light from an object is necessary but is not always available in the normal servicing circumstances. Instead, an optical device called "collimator" is used to produce such an artificial "parallel light" from an object which is often a test chart built into the collimator.
FIG. 1 shows a collimator of prior art denoted by a numeral 30, in FIG. 1, the collimator 30 is built on a bed 40 of sturdy material, a convex lens 32 and an object 33 placed at a focal point of the convex lens 32 are housed in a housing 31, and a light from the object 33 is transformed to a parallel light by the convex lens 32 and is projected out of the housing 31 and to a video camera 50 to be adjusted. The video camera 50 is tentatively installed in the bed 40 upon every servicing by a mounting fixture (not shown). Numeral 51 denotes an objective lens of the video camera 50, and 52 is an image sensor such as a CCD unit installed in the video camera 50. The mounting fixture is not designed exclusively to video cameras but is normally a universal type to accept various types of optical apparatuses such as still cameras and telescopes and the like, for this reason, the fixture is a bulky complex hardware which makes a video camera mounting an awkward and time consuming work, under this installation as shown in FIG. 1, the optical system i.e. a position of the objective lens 51 and/or a position of the image sensor 52 or the like, is adjusted for manufacturing each of mass produced video cameras. This led the present invention by the present inventor.